Electrical connectors are commonly used for attaching electrical conductors, cables, wires, electrical metal tubing (EMT) or the like to an electric box, e.g. a junction box, outlet box, switch box, fuse box, or other similar type of electric box or an electrical mounting panel. Such known electrical connectors are either of a type that are secured to an electric box or electrical panel by a threaded lock nut or by means of a circular snap fit retaining ring of the type disclosed, for example, in U.S. Pat. Nos. 6,860,758; 6,444,907; 5,189,258; 5,266,050; 5,171,164; 2,744,769 and 1,483,218. Reference is also made to U.S. Pat. No. 6,768,057 which is directed to a right angle type connector formed of a pair of sheet metal stampings fitted together and secured to an electrical box with a snap fit arrangement. Connectors formed as connector caps which are adapted to be fitted over the end of a conductor, cable or wires, such as disclosed in U.S. Pat. No. 4,880,387, are also known. Various other known efforts to facilitate the connection of an electrical conductor to an electric box are evidenced by U.S. Pat. Nos. 6,043,432; 6,080,933; 6,114,630; 6,133,529; 6,194,661; 6,335,488; 6,352,439; 6,355,884; 6,444,907; 6,555,750; 6,604,400; 6,670,553; 6,737,584; 6,682,355; 6,780,029 and 6,849,803.
While “snap fit” connectors have been in use for some time, the attachment of such “snap-fit” connectors to an electric box which is concealed in a finished wall is difficult, if not impossible. This is because such “snap fit” retaining rings are formed of spring steel so that the locking tangs, due to the inherent nature of the spring steel, require a good amount of force to flex the locking tangs in order to pass through the conventional knock-out hole to properly seat and lock the connector to a knockout hole of an electric box. For this reason, the installer or user does not have generally sufficient access to the connector assembly so as to apply the necessary force to manually pull the leading end of the connector assembly through the knockout hole due to the relative rigid flexibility of the locking tangs in order to seat and lock the connector assembly to the knockout opening. Usually, the installer or user has to exert a severe pulling force on the wires extending through the connector assembly to seat and lock a snap-fit connector assembly in the knockout hole of an electric box. Applying such pulling force directly on the wires to lock a snap-fit connector assembly to an electric box could seriously damage the conducting wires.
It has also been noted that the typical metallic electrical boxes, e.g. wall boxes, ceiling boxes, junction boxes, electrical panels and the like, which are provided with knock-out openings or holes for receiving an electrical connector assembly, have varying thicknesses. As a result, the degree of electrical grounding that can be attained between the electrical connector assembly and an electric box can vary from box to box. Heretofore, electrical connector assemblies utilizing a so-called external snap fit ring to effect a snap fit connection to an electric box were formed with circumferentially spaced grounding tangs arranged to engage the internal periphery of the knock-out opening provided in such electric boxes to effect the required grounding. As a result, such circumferentially spaced grounding tangs provided only a minimum degree of contact between the electrical connector retainer ring and the metallic electric box or panel for effecting any electrical grounding. The amount of electrical grounding achieved by such grounding tangs may vary from box to box, depending upon the material thickness of a given electric box or panel. As a result, a positive or desired amount of electrical grounding, attained between the connector assembly and the electric box, will vary from installation to installation.